Established anti-aging therapies have dearly shown that science can intercede in the aging process to maximize health and longevity. And indeed, many scientists now regard aging as both a treatable and reversible condition.
Central to the popular acceptance of anti-aging therapy has been the creation of a practical working theory on aging. This theory associates the body's progressive inability at self-repair with hormonal deficiency. The application of this idea, and the unprecedented popularity of hormonal supplementation, testifies to the validity of hormone replacement therapy as an effective means of restoring the body's resilience and ability to self-repair.
Human Growth Hormone, or HGH, has emerged at the forefront of anti-aging therapy. The hormone's ascension has been buttressed by an impressive collection of basic science and clinical findings. The hormone's ability to promote cell regeneration, stimulate tissue repair and bolster the immune system is critical in this forum, since virtually all of the complications of aging stem from the body's inability to repair and replace cells as it loses them.
Theories of Aging
The precise reason why Growth Hormone (GH) levels decrease with advancing age is unknown. However, there are a number of theories that begin to explain this depression within the context of an organism's natural aging process. The theories are as follows:                Oxidative Stress Theory asserts that the body's absorption of oxygen is intricately related to the aging process. The more food a person or animal consumes, the more oxygen the body needs to break it down into energy, and the more rapidly the animal ages due to the creation of free radicals that impair cell function.        The Genetic Theory of Aging asserts that as genetic damage accumulates simply as a consequence of living (i.e. via ongoing cell repair and division), the body's overall efficiency decreases, with aging as a consequence.        The Theory of Somatopause (or Cellular Senescence) asserts that cells are pre-programmed to either die after a finite number of divisions or simply go dormant. As the cells lapse into this phase of their cycle, the efficiency of the organism to maintain its vital functions decreases, until ultimately the organism itself dies.        The Hormonal Theory of Aging asserts that aging is linked to a decline in the body's secretion of a variety of hormones without losing the ability to respond to these hormones. This is the principle basis for hormone replacement therapy with GH.        
Growth Hormone
Growth hormone (G H) is a 191 amino acid long protein that is synthesized and secreted by the pituitary gland found at the base of the brain. The hormone enters the bloodstream in pulses, predominantly at night, and is then quickly metabolized by the liver into the insulin-like growth factors, IGF-1 and IGF-2. (See FIG. 1)
The natural depression of GH secretion with age starts in the mid-twenties and continues as we grow older. By the age of 60, GH levels are typically 15-20% of what they were when a person was in their twenties, sometimes even less.
People that have taken HGH by injection have noticed an overall improvement in their general well-being and vitality, with the following specific reports:                Stronger bones        Enhanced immune system        Accelerated wound healing/tissue regeneration        Decrease in total cholesterol        Increase in muscle mass without exercise        Loss of body fat without exercise        Weight Loss        Improved blood pressure        Younger, more durable skin with fewer wrinkles        Increased energy        Enhanced sexual performance and libido        Increased cardic output        Enhanced exercise performance        Improved mood        Improved memory        Improved sleep pattern        Organ regeneration        Regrowth of lost hair        
Insulin-Like Growth Factors, IGF-1 & IGF-2
GH is released into the bloodstream in small pulsatile bursts during the day that peak during deep sleep. Since the longevity of GH in the bloodstream is very short after its secretion, accurately measuring GH levels directly can be very cumbersome. Consequently, measurement of GH levels is typically achieved indirectly, by measuring for levels of another hormone called Insulin-like Growth Factor 1 (IGF-1).
IGF-1 is produced by the liver in response to circulating GH and remains relatively constant throughout the day in contrast to GH. As such, IGF-1 levels are the standard means to evaluate how much GH the pituitary is releasing, especially when looking for a change over time.
The goal of GH replacement therapy by injection for individuals over 50 is to raise IGF-1 levels to within the range of healthy young adults, which is around 350 μg/m L.
HGH Replacement Supplementation Vs. GH Releasing Factors
It is helpful to understand the relative benefits and risks of HGH replacement supplementation by injection versus the use of an agent that stimulates the release of GH.
GH replacement supplementation by injection can offer substantial benefits, as presented earlier. As with any hormone replacement or supplementation, however, the converse is also true. Poorly monitored HGH supplementation may be associated with allergic reactions, carpal tunnel syndrome, irregularities of bone growth (acromegaly), diabetes and swelling.
Use of a GH Releasing Factor (GHRF), or secretagogue, minimizes the risk of complications associated with GH injections. This decrease in risk is achieved by eliminating the shock of pharmacologic GH injections and the resultant steep increase in IGF-1 levels. By using a GHRF, IGF-1 levels increase more slowly and plateau at levels far below the extremes of GH replacement therapy. Furthermore, healthy advocates of GH supplementation can reasonably use an oral GHRF agent without a physician's involvement.